Pro video blog…Produced by Philip Johnston DoP/Editor


Until FCPX 10.1 and Mavericks Sony’s XAVC “S” was impossible to deal with on my fully spec 27″ iMac with Thunderbolt. The first thing you should note is that 4K comes in two sizes, 17:9 which is known as true 4K (4096 x 2160) and 16:9 which is 3840 x 2160.

It’s not a major problem if you can’t decide what to choose as you can easily change the size in FCPX 10.1.


This is a 16:9 XAVC “S” file on a true 4K timeline (17:9) and as you can see you get two black borders either side of the picture, to sort this scroll down to the Spatial Conform section.

If you have a Sony FDR-AX1 you will find XAVC “S” which has an MPEG 4 wrapper, at 4K you only get the option of 3840 x 2160 which is 16:9. The good news is that FCPX 10.1 has nailed the ingest of this complicated codec and takes no longer than XAVC to import.


You will get three options, Fit…Fill…None, use the “Fill” option and you will lose your two black borders. If you have Full HD footage (1920 x 1080) and you choose “None”under Spatial Conform you can fit four HD shots into one 4K page.


Interestingly I decided to fit a 1920 x 1080 picture into a 4096 4K timeline to see what the quality loss would be and the simple answer is very little, I was surprised at this but will give me great confidence in the future if I have to mix and match HD and 4K material.

FCPX 10.1 with Mavericks is a game changer for 4K in general, Sony’s XAVC “S” did not work with FCPX 10.0.9 and Mountain Lion. Apple have done their homework with Mavericks but combine this with FCPX 10.1 and you get a very slick, responsive editing system add that to a new MacPro and 4K becomes even more fantastic.


Having been working in the video business since 1988 I have amassed a great amount of knowledge of both the kit and production values over the last 30 years.

5 thoughts on “Working in 4K with FCPX 10.1 with good news for XAVC “S” users !

  1. One of the key parts of 4K and its new colour space and 10 bit foundation is that 10 bit 4:2:2 HD up scaled to a 2:1 ratio looks good on a way that 8 bit 4:2:2 doesn’t!

    Going forward, I’ve resolved that I have purchased my last 8 bit camera, it’s 10 bit HD origination from now on.

  2. This is done automatically in Vegas Pro 12 and Edius Pro 7 depending on project setup. They can of course reset to source sizes for cropping or interpolation depending on project settings. As I understand most 4K TV’s are 3840×2160, 16×9 and true 4K is really a cinema size needing scaling to show on a “4K” TV. So if shooting for TV it is 3840×2160.

  3. I would like to buy fdr x1. but I can not figure out if xavc-s is natively supported by Final Cut x. help! thanks

    HDW : Hi Simone the best I can offer is that before 10.1 XAVC “S” was a dog and took forever to import, after 10.1 I got instant thumbnails and imported very quickly though Apple did say 4K support had been re-engineered for 10.1, hope this helps.

  4. so I can buy fdr x1?
    final cut x 10.1 in working files natively?
    with a 2012 mac pro 6-core, 32 gb ram, 2 ssd mounting fluid would be?
    you can have an original file to test?
    sorry for trouble!

    HDW : I have my own XAVC S files thanks, remember to download the XAVC driver from Sony. A 2012 MacPro will be fine with Mavericks which is the first program to check as FCPX 10.1 won’t run with Mountain Lion etc. Apple state a MacPro 2008 upwards to be comparable with Mavericks.

  5. Question, Does anyone have any 4k footage to try out in my FCPX MBPRO ? its a 2011 with 16 gigs ram and a 500 gig SSD

    Would love to see how bad its going to be on this thing, I dont want to mess with buying a new mac pro, im tooooo invested in my photography to do this for home videos..

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